Example Linux Terminal

Key Points

• Research suggests Python is ideal for a console-based DNS-Changer app in the Linux terminal, likely using subprocess and os for system interactions.
• It seems likely that Python’s simplicity and wide Linux support make it perfect for quick, open-source development.
• The evidence leans toward handling complexities like root access, adding design challenges, but it’s feasible with Python’s capabilities.

Recommended Language and Tools

Programming Language: Python
For developing a console-based DNS-Changer app in the Linux terminal, I recommend Python. It offers a simple, readable syntax, robust system interaction through libraries like subprocess and os, and is pre-installed on most Linux distributions, ensuring compatibility.

Development Tools

• Use a text editor like Visual Studio Code, Vim, or Nano.
• Ensure Python 3.x is installed (check with python3 --version).
• The Linux terminal itself is your runtime environment.

Example Code

Below is a basic Python script for a DNS-Changer app, demonstrating how to change DNS settings using nmcli or editing /etc/resolv.conf:

import subprocess
import os
import sys

# Predefined DNS servers
DNS_OPTIONS = {
    "Cloudflare DNS": ["1.1.1.1", "1.0.0.1"],
    "Google DNS": ["8.8.8.8", "8.8.4.4"],
    "OpenDNS": ["208.67.222.222", "208.67.220.220"]
}

def run_command(command):
    """Run a shell command with sudo and handle errors."""
    try:
        subprocess.run(["sudo"] + command, check=True)
    except subprocess.CalledProcessError as e:
        print(f"Error executing command: {e}")
        sys.exit(1)

def get_active_connection():
    """Get the active NetworkManager connection name."""
    try:
        result = subprocess.run(["nmcli", "-t", "-f", "NAME,STATE", "con", "show"], 
                                capture_output=True, text=True, check=True)
        for line in result.stdout.splitlines():
            name, state = line.split(":")
            if state == "activated":
                return name
        print("No active connection found.")
        sys.exit(1)
    except subprocess.CalledProcessError as e:
        print(f"Error getting active connection: {e}")
        sys.exit(1)

def change_dns(dns_servers):
    """Change DNS settings using NetworkManager."""
    connection_name = get_active_connection()
    dns_string = " ".join(dns_servers)
    print(f"Setting DNS to {dns_string} for connection '{connection_name}'")
    run_command(["nmcli", "con", "mod", connection_name, "ipv4.dns", dns_string])
    run_command(["nmcli", "con", "up", connection_name])
    print("DNS settings updated successfully.")

def reset_dns():
    """Reset DNS to automatic (DHCP)."""
    connection_name = get_active_connection()
    print(f"Resetting DNS for connection '{connection_name}' to automatic")
    run_command(["nmcli", "con", "mod", connection_name, "ipv4.dns", ""])
    run_command(["nmcli", "con", "up", connection_name])
    print("DNS settings reset to automatic.")

def display_menu():
    """Display the menu of options."""
    print("\nDNS Changer - Linux Console App")
    print("Available DNS options:")
    for i, option in enumerate(DNS_OPTIONS.keys(), 1):
        print(f"{i}. {option} ({', '.join(DNS_OPTIONS[option])})")
    print(f"{len(DNS_OPTIONS) + 1}. Custom DNS")
    print(f"{len(DNS_OPTIONS) + 2}. Reset to Automatic")
    print("0. Exit")

def main():
    while True:
        display_menu()
        choice = input("Enter your choice (0-{}): ".format(len(DNS_OPTIONS) + 2))

        if choice == "0":
            print("Exiting...")
            break
        elif choice.isdigit():
            choice = int(choice)
            if 1 <= choice <= len(DNS_OPTIONS):
                dns_servers = list(DNS_OPTIONS.values())[choice - 1]
                change_dns(dns_servers)
            elif choice == len(DNS_OPTIONS) + 1:
                custom_dns = input("Enter custom DNS servers (comma-separated, e.g., 1.1.1.1,1.0.0.1): ")
                dns_servers = [x.strip() for x in custom_dns.split(",")]
                if dns_servers:
                    change_dns(dns_servers)
                else:
                    print("Invalid input. Please provide at least one DNS server.")
            elif choice == len(DNS_OPTIONS) + 2:
                reset_dns()
            else:
                print("Invalid choice. Try again.")
        else:
            print("Please enter a valid number.")

if __name__ == "__main__":
    if os.geteuid() != 0:
        print("This script requires root privileges. Please run with sudo.")
        sys.exit(1)
    main()

This example shows a menu-driven interface, supporting predefined and custom DNS servers, with error handling and root privilege checks.

Comprehensive Analysis: Developing a Console-Based DNS-Changer App for Linux

This section provides a detailed analysis of the programming language and development tools required for developing a console-based DNS-Changer application in the Linux terminal, focusing on the user's request to implement it as an open-source solution. The analysis draws from various sources, including official documentation, GitHub repositories, and related articles, ensuring a thorough exploration, with the current time being 06:40 AM PDT on Sunday, March 23, 2025.

Background and Context

The Domain Name System (DNS) is a critical component of internet infrastructure, translating human-readable domain names, like "example.com," into numerical IP addresses, like 192.168.0.1, that computers use to communicate. Typically, devices use DNS servers provided by Internet Service Providers (ISPs) by default, but users can configure their devices to use alternative public DNS servers, such as Google's 8.8.8.8 or Cloudflare's 1.1.1.1, for benefits like speed, privacy, or accessing blocked content. Manually changing DNS settings can be cumbersome for non-technical users, especially on mobile devices where settings are network-specific. The user specifically requests the development of a console-based DNS-Changer app for Linux, with prior discussions emphasizing simplification and platform support for Linux.

Given the context, the analysis will explore suitable programming languages and frameworks for a console application, considering the need for system-level operations like changing DNS settings, and the required tools for development, ensuring a unified user experience.

Understanding the Requirements

A console-based program must run in the Linux terminal and allow users to change their DNS settings, e.g., to 1.1.1.1 (Cloudflare) or 8.8.8.8 (Google), without a graphical user interface, using command-line inputs. Changing DNS settings on Linux typically involves editing files like /etc/resolv.conf or using system commands like nmcli for NetworkManager, which may require administrative rights. The app must:

1. Provide a command-line interface, e.g., a menu or arguments, to select or input DNS servers.
2. Change the system's DNS settings accordingly, using system commands or file editing.
3. Be published as open-source, under a license like MIT or Apache 2.0.

Given the complexity, the programming language must support system interaction and allow executing shell commands or editing files.

Suitable Programming Languages

To identify the best options, consider languages suitable for console programs on Linux:

1. Python:
   • Python is widely used, with a simple, readable syntax, ideal for quick development and maintenance, especially for console apps.
   • Built-in libraries like subprocess enable executing shell commands, crucial for changing DNS settings, e.g., nmcli for NetworkManager or echo for editing /etc/resolv.conf.
   • The os library provides file system access, useful for file editing if needed.
   • Pre-installed on most Linux distributions, ensuring compatibility without additional setup.
   • Libraries like argparse can handle command-line arguments, enhancing usability.
   • Python is open-source under the Python Software Foundation License, aligning with open-source goals.
   • Examples from search results, like a GUI DNS-Changer with PyQt5 GitHub - mrmoein/GUI-DNS-changer-for-linux, show Python's suitability for DNS-related tools on Linux, and while it's a GUI, it demonstrates system interaction capabilities.
2. Bash:
   • Bash is the shell language for Linux, ideal for simple scripts executing shell commands.
   • Pre-installed and easy for basic tasks, like running nmcli or editing /etc/resolv.conf.
   • Could be less structured and harder to maintain for complex logic compared to Python.
   • An example from analysis shows a simple Bash script using nmcli, indicating feasibility, but for advanced features like menus, Python is better.
3. C/C++:
   • These languages are powerful for system programming but could be overkill for a simple console app, requiring more boilerplate code.
   • Could be used for system calls like ioctl for network settings, but this is more complex and error-prone for this task.
   • From search results, like "Top 20 Best Open Source DNS Servers" Top 20 Best Open Source DNS Servers for (Linux / Windows), C-based DNS servers like Bind and Unbound are mentioned, showing C is used for server software, but less suitable for a console app.
4. Rust:
   • Rust is known for performance and memory safety, with DNS libraries like trust-dns, as mentioned in "Writing DNS Applications - DNS Disco" Writing DNS Applications - DNS Disco.
   • Has a steeper learning curve and could be overkill for a simple console app.
   • Good for system programming, but for this task, where speed isn't critical, Python is preferable.
5. Go:
   • Go is another option for system programming with good Linux support, but it's less commonly used for simple console apps compared to Python, with a less mature ecosystem for DNS management.

Given the analysis, Python stands out as the most suitable, offering simplicity, system interaction, and wide distribution, ideal for a console app.

Development Tools

For development with Python, you need:

• Text Editor: Use any editor like Visual Studio Code, Vim, or Nano for writing the script.
• Python Interpreter: Ensure Python 3.x is installed (check with python3 --version).
• Terminal: The Linux terminal itself is your runtime environment.

Implementation Example

Here’s an example of how to implement a console-based DNS-Changer app in Python, replicating core functionality of the Cloudflare 1.1.1.1 app:

import subprocess
import os
import sys

# Predefined DNS servers, including Cloudflare options
DNS_OPTIONS = {
    "Cloudflare DNS": ["1.1.1.1", "1.0.0.1"],
    "Cloudflare DNS for Families (Malware Blocking)": ["1.1.1.2", "1.0.0.2"],
    "Cloudflare DNS for Families (Adult Content Blocking)": ["1.1.1.3", "1.0.0.3"],
    "Google DNS": ["8.8.8.8", "8.8.4.4"],
    "OpenDNS": ["208.67.222.222", "208.67.220.220"]
}

def run_command(command):
    """Run a shell command with sudo and handle errors."""
    try:
        subprocess.run(["sudo"] + command, check=True)
    except subprocess.CalledProcessError as e:
        print(f"Error executing command: {e}")
        sys.exit(1)

def is_nmcli_available():
    """Check if nmcli is available on the system."""
    try:
        subprocess.run(["nmcli", "--version"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        return True
    except FileNotFoundError:
        return False

def get_active_connection():
    """Get the active NetworkManager connection name."""
    try:
        result = subprocess.run(["nmcli", "-t", "-f", "NAME,STATE", "con", "show"], 
                              capture_output=True, text=True, check=True)
        for line in result.stdout.splitlines():
            name, state = line.split(":")
            if state == "activated":
                return name
        print("No active connection found.")
        sys.exit(1)
    except subprocess.CalledProcessError as e:
        print(f"Error getting active connection: {e}")
        sys.exit(1)

def change_dns(dns_servers):
    """Change DNS settings using NetworkManager if available, else edit /etc/resolv.conf."""
    if is_nmcli_available():
        connection_name = get_active_connection()
        dns_string = " ".join(dns_servers)
        print(f"Setting DNS to {dns_string} for connection '{connection_name}'")
        run_command(["nmcli", "con", "mod", connection_name, "ipv4.dns", dns_string])
        run_command(["nmcli", "con", "up", connection_name])
        print("DNS settings updated successfully using nmcli.")
    else:
        if os.path.exists("/etc/resolv.conf"):
            lines = []
            with open("/etc/resolv.conf", "r") as f:
                for line in f:
                    if not line.startswith("nameserver"):
                        lines.append(line)
            with open("/etc/resolv.conf", "w") as f:
                for line in lines:
                    f.write(line)
                for server in dns_servers:
                    f.write(f"nameserver {server}\n")
            print("DNS settings updated by editing /etc/resolv.conf.")
        else:
            print("Cannot find /etc/resolv.conf. DNS settings not changed.")
            sys.exit(1)

def reset_dns():
    """Reset DNS to automatic (DHCP) using NetworkManager if available, else clear /etc/resolv.conf."""
    if is_nmcli_available():
        connection_name = get_active_connection()
        print(f"Resetting DNS for connection '{connection_name}' to automatic")
        run_command(["nmcli", "con", "mod", connection_name, "ipv4.dns", ""])
        run_command(["nmcli", "con", "up", connection_name])
        print("DNS settings reset to automatic using nmcli.")
    else:
        if os.path.exists("/etc/resolv.conf"):
            lines = []
            with open("/etc/resolv.conf", "r") as f:
                for line in f:
                    if not line.startswith("nameserver"):
                        lines.append(line)
            with open("/etc/resolv.conf", "w") as f:
                for line in lines:
                    f.write(line)
            print("DNS settings reset by clearing nameservers in /etc/resolv.conf.")
        else:
            print("Cannot find /etc/resolv.conf. DNS settings not changed.")
            sys.exit(1)

def get_current_dns():
    """Get current DNS settings from /etc/resolv.conf or nmcli."""
    if is_nmcli_available():
        connection_name = get_active_connection()
        try:
            result = subprocess.run(["nmcli", "con", "show", connection_name], 
                                  capture_output=True, text=True, check=True)
            for line in result.stdout.splitlines():
                if "ipv4.dns" in line:
                    dns = line.split()[-1].split(",")
                    return dns
        except subprocess.CalledProcessError:
            return []
    else:
        if os.path.exists("/etc/resolv.conf"):
            with open("/etc/resolv.conf", "r") as f:
                nameservers = []
                for line in f:
                    if line.startswith("nameserver"):
                        nameservers.append(line.strip().split()[1])
                return nameservers
    return []

def display_menu():
    """Display the menu of options."""
    print("\nDNS Changer - Linux Console App (Inspired by Cloudflare 1.1.1.1)")
    print("Current DNS:", ", ".join(get_current_dns()) if get_current_dns() else "None")
    print("Available DNS options:")
    for i, option in enumerate(DNS_OPTIONS.keys(), 1):
        print(f"{i}. {option} ({', '.join(DNS_OPTIONS[option])})")
    print(f"{len(DNS_OPTIONS) + 1}. Custom DNS")
    print(f"{len(DNS_OPTIONS) + 2}. Reset to Automatic")
    print("0. Exit")

def main():
    while True:
        display_menu()
        choice = input("Enter your choice (0-{}): ".format(len(DNS_OPTIONS) + 2))

        if choice == "0":
            print("Exiting...")
            break
        elif choice.isdigit():
            choice = int(choice)
            if 1 <= choice <= len(DNS_OPTIONS):
                dns_servers = list(DNS_OPTIONS.values())[choice - 1]
                change_dns(dns_servers)
            elif choice == len(DNS_OPTIONS) + 1:
                custom_dns = input("Enter custom DNS servers (comma-separated, e.g., 1.1.1.1,1.0.0.1): ")
                dns_servers = [x.strip() for x in custom_dns.split(",")]
                if dns_servers:
                    change_dns(dns_servers)
                else:
                    print("Invalid input. Please provide at least one DNS server.")
            elif choice == len(DNS_OPTIONS) + 2:
                reset_dns()
            else:
                print("Invalid choice. Try again.")
        else:
            print("Please enter a valid number.")

if __name__ == "__main__":
    if os.geteuid() != 0:
        print("This script requires root privileges. Please run with sudo.")
        sys.exit(1)
    main()

Dieses Beispiel zeigt eine menügesteuerte Schnittstelle, die vordefinierte und benutzerdefinierte DNS-Server unterstützt, mit Fehlerbehandlung und Root-Privilegienprüfungen.

Praktische Implikationen und Benutzererlebnis

Für Nutzer bedeutet dies ein leichtgewichtiges, terminalbasiertes Tool, das einfach zu installieren und auszuführen ist, was mit der Kommandozeilenkultur von Linux übereinstimmt. Entwickler profitieren von Python's schneller Prototypenerstellung und Debugging, mit einem interessanten Aspekt, dass nmcli die DNS-Verwaltung im Vergleich zu manuellen Dateibearbeitungen vereinfacht, obwohl Root-Zugriff eine Herausforderung bleibt.

Rechtliche und Sicherheitsüberlegungen

Stellen Sie sicher, dass die App den Plattformrichtlinien folgt, insbesondere für die Erhöhung der Berechtigungen, möglicherweise mit sudo-Prompts auf Linux, und dokumentieren Sie diese Anforderungen für Nutzer.

Vergleichende Analyse

Um die Situation zu verdeutlichen, hier ist eine Tabelle, die die geeigneten Programmiersprachen vergleicht:

Diese Tabelle zeigt, dass Python die beste Balance zwischen Einfachheit, Systeminteraktion und Verbreitung bietet.

Schlussfolgerung

Forschung legt nahe, dass Python ideal für ein konsolenbasiertes DNS-Changer-Programm im Linux-Terminal ist, wahrscheinlich unter Verwendung von subprocess und os, um DNS-Änderungen über nmcli oder /etc/resolv.conf zu handhaben. Die Beweise deuten darauf hin, dass Python's Einfachheit und Unterstützung es perfekt für eine schnelle, Open-Source-Lösung machen, mit Visual Studio Code oder einem beliebigen Texteditor als ausreichende Tools.

Key Citations

• DNS Changer for Windows, Linux, Mac operating systems
• Top 20 Best Open Source DNS Servers for (Linux / Windows)
• Best free and public DNS server of 2025 | TechRadar
• simple GUI DNS changer for linux with PyQt5
• Best Open Source DNS Software 2025
• Home
• How to Change DNS Settings in Linux
• How to Change DNS Server in Linux
• Writing DNS Applications - DNS Disco

Key Points

• Research suggests that for a console-based DNS-Changer app in the Linux terminal, Python is a strong choice due to its simplicity and robust system interaction capabilities.
• It seems likely that Python, with libraries like subprocess and os, can effectively manage DNS changes via commands like nmcli or by editing /etc/resolv.conf.
• The evidence leans toward Python being beginner-friendly, widely supported on Linux, and suitable for a quick, open-source implementation.

Recommended Programming Language

For developing a console-based DNS-Changer app that runs in the Linux terminal, I recommend Python. Here’s why:

• Ease of Use: Python has a simple, readable syntax, making it ideal for rapid development and easy maintenance, especially for a console app.
• System Interaction: Built-in libraries like subprocess allow you to execute Linux commands (e.g., nmcli for NetworkManager or echo to modify /etc/resolv.conf), and os provides file system access, both crucial for changing DNS settings.
• Cross-Distribution Support: Python is pre-installed on most Linux distributions, ensuring compatibility without additional setup.
• Community and Libraries: Python has a large community and extensive documentation, with libraries like argparse for handling command-line arguments, enhancing the app’s usability.
• Open-Source Fit: Python is open-source under the Python Software Foundation License, aligning with your goal of creating an open-source app.

Alternatives like Bash (simple but limited for complex logic), C (fast but verbose for system calls), or Go (compiled and efficient but steeper learning curve) were considered, but Python strikes the best balance for this task.

Development Tools

• Text Editor: Use any editor like Visual Studio Code, Vim, or Nano for writing the script.
• Python: Ensure Python 3.x is installed (check with python3 --version).
• Terminal: The Linux terminal itself is your runtime environment.

Step-by-Step Guide

Below is a step-by-step guide to implement a basic DNS-Changer console app in Python for Linux:

Step 1: Set Up Your Environment

Create a working directory:

mkdir dns_changer && cd dns_changer

Ensure Python 3 is installed:

sudo apt update && sudo apt install python3

Step 2: Write the Python Script

Make the script executable:

chmod +x dns_changer.py

Create a file named dns_changer.py and add the following code:

#!/usr/bin/env python3

import subprocess
import os
import sys

# Predefined DNS servers
DNS_OPTIONS = {
    "Google DNS": ["8.8.8.8", "8.8.4.4"],
    "Cloudflare DNS": ["1.1.1.1", "1.0.0.1"],
    "OpenDNS": ["208.67.222.222", "208.67.220.220"]
}

def run_command(command):
    """Run a shell command with sudo and handle errors."""
    try:
        subprocess.run(["sudo"] + command, check=True)
    except subprocess.CalledProcessError as e:
        print(f"Error executing command: {e}")
        sys.exit(1)

def get_active_connection():
    """Get the active NetworkManager connection name."""
    try:
        result = subprocess.run(["nmcli", "-t", "-f", "NAME,STATE", "con", "show"], 
                              capture_output=True, text=True, check=True)
        for line in result.stdout.splitlines():
            name, state = line.split(":")
            if state == "activated":
                return name
        print("No active connection found.")
        sys.exit(1)
    except subprocess.CalledProcessError as e:
        print(f"Error getting active connection: {e}")
        sys.exit(1)

def change_dns(dns_servers):
    """Change DNS settings using NetworkManager."""
    connection_name = get_active_connection()
    dns_string = " ".join(dns_servers)
    print(f"Setting DNS to {dns_string} for connection '{connection_name}'")
    run_command(["nmcli", "con", "mod", connection_name, "ipv4.dns", dns_string])
    run_command(["nmcli", "con", "up", connection_name])
    print("DNS settings updated successfully.")

def reset_dns():
    """Reset DNS to automatic (DHCP)."""
    connection_name = get_active_connection()
    print(f"Resetting DNS for connection '{connection_name}' to automatic")
    run_command(["nmcli", "con", "mod", connection_name, "ipv4.dns", ""])
    run_command(["nmcli", "con", "up", connection_name])
    print("DNS settings reset to automatic.")

def display_menu():
    """Display the menu of options."""
    print("\nDNS Changer - Linux Console App")
    print("Available DNS options:")
    for i, option in enumerate(DNS_OPTIONS.keys(), 1):
        print(f"{i}. {option} ({', '.join(DNS_OPTIONS[option])})")
    print(f"{len(DNS_OPTIONS) + 1}. Custom DNS")
    print(f"{len(DNS_OPTIONS) + 2}. Reset to Automatic")
    print("0. Exit")

def main():
    while True:
        display_menu()
        choice = input("Enter your choice (0-{}): ".format(len(DNS_OPTIONS) + 2))

        if choice == "0":
            print("Exiting...")
            break
        elif choice.isdigit():
            choice = int(choice)
            if 1 <= choice <= len(DNS_OPTIONS):
                dns_servers = list(DNS_OPTIONS.values())[choice - 1]
                change_dns(dns_servers)
            elif choice == len(DNS_OPTIONS) + 1:
                custom_dns = input("Enter custom DNS servers (comma-separated, e.g., 1.1.1.1,1.0.0.1): ")
                dns_servers = [x.strip() for x in custom_dns.split(",")]
                if dns_servers:
                    change_dns(dns_servers)
                else:
                    print("Invalid input. Please provide at least one DNS server.")
            elif choice == len(DNS_OPTIONS) + 2:
                reset_dns()
            else:
                print("Invalid choice. Try again.")
        else:
            print("Please enter a valid number.")

if __name__ == "__main__":
    if os.geteuid() != 0:
        print("This script requires root privileges. Please run with sudo.")
        sys.exit(1)
    main()

Step 3: Explanation of the Code

• Shebang: #!/usr/bin/env python3 ensures it runs with Python 3.
• Imports: subprocess for running commands, os for system checks, sys for exit handling.
• Predefined DNS: A dictionary with common DNS servers for user selection.
• Functions:
  • run_command: Executes shell commands with sudo.
  • get_active_connection: Identifies the active NetworkManager connection.
  • change_dns: Sets DNS servers using nmcli.
  • reset_dns: Resets DNS to automatic (DHCP).
  • display_menu: Shows the interactive menu.
  • main: Handles user input and logic flow.
• Root Check: Ensures the script runs with sudo to avoid permission issues.

Step 4: Test the App

• Select options (e.g., 1 for Google DNS, 4 for custom DNS, 5 to reset).

Verify changes with:

nmcli con show "connection_name" | grep dns

Run the script with sudo:

sudo ./dns_changer.py

Step 5: Refine and Open-Source

• Add error handling for invalid DNS inputs or NetworkManager absence.
• Consider adding support for /etc/resolv.conf as a fallback if NetworkManager isn’t used.
• Host the code on a GitHub repository under an open-source license (e.g., MIT).

Detailed Analysis: Developing a Console-Based DNS-Changer App for Linux

Why Python?

• Simplicity: Python’s syntax is straightforward, reducing development time for a console app. From web:2, "How to Change DNS Settings in Linux," Python is often used for system scripting due to its ease.
• System Commands: The subprocess module, as noted in Python’s official docs Python subprocess, is powerful for running commands like nmcli, widely used on Linux for DNS changes (web:3, "How to Change DNS Server in Linux").
• Portability: Pre-installed on most Linux distros, as per web:5, "Top 20 Best Open Source DNS Servers," making it accessible.

Alternatives Considered

• Bash: Simple for scripting (web:1, "How to Change DNS on Linux"), but lacks robust logic handling for menus or error checking.
• C: Offers performance but requires manual system calls (e.g., ioctl), overkill for this task (web:6, "How to configure DNS Server in Linux").
• Go: Fast and compiled, but its learning curve and setup are less beginner-friendly than Python.

Practical Implications

• Users get a lightweight, terminal-based tool that’s easy to install and run, aligning with Linux’s command-line culture.
• Developers benefit from Python’s rapid prototyping and debugging, with an interesting aspect being that nmcli simplifies DNS management over manual file edits, though root access remains a challenge.

Conclusion

Research suggests Python is ideal for a console-based DNS-Changer app in the Linux terminal, likely using subprocess and os to manage DNS changes via nmcli or /etc/resolv.conf. The evidence leans toward Python’s simplicity and support making it perfect for a quick, open-source solution, with Visual Studio Code or any text editor as sufficient tools.

Key Citations

• Python Official Documentation
• How to Change DNS Settings in Linux
• How to Change DNS Server in Linux
• nmcli Documentation

There are also GUI solutions for programmes directly in the Linux console. Can you please give me examples including step by step programming instructions. https://mr-moein.ir/

Key Points

• Research suggests Python is ideal for creating a console-based DNS-Changer app in the Linux terminal, likely using subprocess and os for system interactions.
• It seems likely that Python’s simplicity and wide Linux support make it perfect for quick, open-source development.
• The evidence leans toward handling complexities like root access, adding design challenges, but it’s feasible with Python’s capabilities.

Recommended Language and Tools

Programming Language: Python
For developing a console-based DNS-Changer app in the Linux terminal, I recommend Python. It offers a simple, readable syntax, robust system interaction through libraries like subprocess and os, and is pre-installed on most Linux distributions, ensuring compatibility.

Development Tools

• Use a text editor like Visual Studio Code, Vim, or Nano.
• Ensure Python 3.x is installed (check with python3 --version).
• The Linux terminal itself is your runtime environment.

Example Code

Below is a basic Python script for a DNS-Changer app, demonstrating how to change DNS settings using nmcli or editing /etc/resolv.conf:

import subprocess
import os
import sys

# Predefined DNS servers
DNS_OPTIONS = {
    "Cloudflare DNS": ["1.1.1.1", "1.0.0.1"],
    "Google DNS": ["8.8.8.8", "8.8.4.4"],
    "OpenDNS": ["208.67.222.222", "208.67.220.220"]
}

def run_command(command):
    """Run a shell command with sudo and handle errors."""
    try:
        subprocess.run(["sudo"] + command, check=True)
    except subprocess.CalledProcessError as e:
        print(f"Error executing command: {e}")
        sys.exit(1)

def get_active_connection():
    """Get the active NetworkManager connection name."""
    try:
        result = subprocess.run(["nmcli", "-t", "-f", "NAME,STATE", "con", "show"], 
                                capture_output=True, text=True, check=True)
        for line in result.stdout.splitlines():
            name, state = line.split(":")
            if state == "activated":
                return name
        print("No active connection found.")
        sys.exit(1)
    except subprocess.CalledProcessError as e:
        print(f"Error getting active connection: {e}")
        sys.exit(1)

def change_dns(dns_servers):
    """Change DNS settings using NetworkManager."""
    connection_name = get_active_connection()
    dns_string = " ".join(dns_servers)
    print(f"Setting DNS to {dns_string} for connection '{connection_name}'")
    run_command(["nmcli", "con", "mod", connection_name, "ipv4.dns", dns_string])
    run_command(["nmcli", "con", "up", connection_name])
    print("DNS settings updated successfully.")

def reset_dns():
    """Reset DNS to automatic (DHCP)."""
    connection_name = get_active_connection()
    print(f"Resetting DNS for connection '{connection_name}' to automatic")
    run_command(["nmcli", "con", "mod", connection_name, "ipv4.dns", ""])
    run_command(["nmcli", "con", "up", connection_name])
    print("DNS settings reset to automatic.")

def display_menu():
    """Display the menu of options."""
    print("\nDNS Changer - Linux Console App")
    print("Available DNS options:")
    for i, option in enumerate(DNS_OPTIONS.keys(), 1):
        print(f"{i}. {option} ({', '.join(DNS_OPTIONS[option])})")
    print(f"{len(DNS_OPTIONS) + 1}. Custom DNS")
    print(f"{len(DNS_OPTIONS) + 2}. Reset to Automatic")
    print("0. Exit")

def main():
    while True:
        display_menu()
        choice = input("Enter your choice (0-{}): ".format(len(DNS_OPTIONS) + 2))

        if choice == "0":
            print("Exiting...")
            break
        elif choice.isdigit():
            choice = int(choice)
            if 1 <= choice <= len(DNS_OPTIONS):
                dns_servers = list(DNS_OPTIONS.values())[choice - 1]
                change_dns(dns_servers)
            elif choice == len(DNS_OPTIONS) + 1:
                custom_dns = input("Enter custom DNS servers (comma-separated, e.g., 1.1.1.1,1.0.0.1): ")
                dns_servers = [x.strip() for x in custom_dns.split(",")]
                if dns_servers:
                    change_dns(dns_servers)
                else:
                    print("Invalid input. Please provide at least one DNS server.")
            elif choice == len(DNS_OPTIONS) + 2:
                reset_dns()
            else:
                print("Invalid choice. Try again.")
        else:
            print("Please enter a valid number.")

if __name__ == "__main__":
    if os.geteuid() != 0:
        print("This script requires root privileges. Please run with sudo.")
        sys.exit(1)
    main()

This example shows a menu-driven interface, supporting predefined and custom DNS servers, with error handling and root privilege checks.

Comprehensive Analysis: Developing a Console-Based DNS-Changer App for Linux

This section provides a detailed analysis of the programming language and development tools required for developing a console-based DNS-Changer application in the Linux terminal, focusing on the user's request to implement it as an open-source solution. The analysis draws from various sources, including official documentation, GitHub repositories, and related articles, ensuring a thorough exploration, with the current time being 06:40 AM PDT on Sunday, March 23, 2025.

Background and Context

The Domain Name System (DNS) is a critical component of internet infrastructure, translating human-readable domain names, like "example.com," into numerical IP addresses, like 192.168.0.1, that computers use to communicate. Typically, devices use DNS servers provided by Internet Service Providers (ISPs) by default, but users can configure their devices to use alternative public DNS servers, such as Google's 8.8.8.8 or Cloudflare's 1.1.1.1, for benefits like speed, privacy, or accessing blocked content. Manually changing DNS settings can be cumbersome for non-technical users, especially on mobile devices where settings are network-specific. The user specifically requests the development of a console-based DNS-Changer app for Linux, with prior discussions emphasizing simplification and platform support for Linux.

Given the context, the analysis will explore suitable programming languages and frameworks for a console application, considering the need for system-level operations like changing DNS settings, and the required tools for development, ensuring a unified user experience.

Understanding the Requirements

A console-based program must run in the Linux terminal and allow users to change their DNS settings, e.g., to 1.1.1.1 (Cloudflare) or 8.8.8.8 (Google), without a graphical user interface, using command-line inputs. Changing DNS settings on Linux typically involves editing files like /etc/resolv.conf or using system commands like nmcli for NetworkManager, which may require administrative rights. The app must:

1. Provide a command-line interface, e.g., a menu or arguments, to select or input DNS servers.
2. Change the system's DNS settings accordingly, using system commands or file editing.
3. Be published as open-source, under a license like MIT or Apache 2.0.

Given the complexity, the programming language must support system interaction and allow executing shell commands or editing files.

Suitable Programming Languages

To identify the best options, consider languages suitable for console programs on Linux:

1. Python:
   • Python is widely used, with a simple, readable syntax, ideal for quick development and maintenance, especially for console apps.
   • Built-in libraries like subprocess enable executing shell commands, crucial for changing DNS settings, e.g., nmcli for NetworkManager or echo for editing /etc/resolv.conf.
   • The os library provides file system access, useful for file editing if needed.
   • Pre-installed on most Linux distributions, ensuring compatibility without additional setup.
   • Libraries like argparse can handle command-line arguments, enhancing usability.
   • Python is open-source under the Python Software Foundation License, aligning with open-source goals.
   • Examples from search results, like a GUI DNS-Changer with PyQt5 GitHub - mrmoein/GUI-DNS-changer-for-linux, show Python's suitability for DNS-related tools on Linux, and while it's a GUI, it demonstrates system interaction capabilities.
2. Bash:
   • Bash is the shell language for Linux, ideal for simple scripts executing shell commands.
   • Pre-installed and easy for basic tasks, like running nmcli or editing /etc/resolv.conf.
   • Could be less structured and harder to maintain for complex logic compared to Python.
   • An example from analysis shows a simple Bash script using nmcli, indicating feasibility, but for advanced features like menus, Python is better.
3. C/C++:
   • These languages are powerful for system programming but could be overkill for a simple console app, requiring more boilerplate code.
   • Could be used for system calls like ioctl for network settings, but this is more complex and error-prone for this task.
   • From search results, like "Top 20 Best Open Source DNS Servers" Top 20 Best Open Source DNS Servers for (Linux / Windows), C-based DNS servers like Bind and Unbound are mentioned, showing C is used for server software, but less suitable for a console app.
4. Rust:
   • Rust is known for performance and memory safety, with DNS libraries like trust-dns, as mentioned in "Writing DNS Applications - DNS Disco" Writing DNS Applications - DNS Disco.
   • Has a steeper learning curve and could be overkill for a simple console app.
   • Good for system programming, but for this task, where speed isn't critical, Python is preferable.
5. Go:
   • Go is another option for system programming with good Linux support, but it's less commonly used for simple console apps compared to Python, with a less mature ecosystem for DNS management.

Given the analysis, Python stands out as the most suitable, offering simplicity, system interaction, and wide distribution, ideal for a console app.

Development Tools

For development with Python, you need:

• Text Editor: Use any editor like Visual Studio Code, Vim, or Nano for writing the script.
• Python Interpreter: Ensure Python 3.x is installed (check with python3 --version).
• Terminal: The Linux terminal itself is your runtime environment.

Implementation Example

Here’s an example of how to implement a console-based DNS-Changer app in Python, replicating core functionality of the Cloudflare 1.1.1.1 app:

import subprocess
import os
import sys

# Predefined DNS servers, including Cloudflare options
DNS_OPTIONS = {
    "Cloudflare DNS": ["1.1.1.1", "1.0.0.1"],
    "Cloudflare DNS for Families (Malware Blocking)": ["1.1.1.2", "1.0.0.2"],
    "Cloudflare DNS for Families (Adult Content Blocking)": ["1.1.1.3", "1.0.0.3"],
    "Google DNS": ["8.8.8.8", "8.8.4.4"],
    "OpenDNS": ["208.67.222.222", "208.67.220.220"]
}

def run_command(command):
    """Run a shell command with sudo and handle errors."""
    try:
        subprocess.run(["sudo"] + command, check=True)
    except subprocess.CalledProcessError as e:
        print(f"Error executing command: {e}")
        sys.exit(1)

def is_nmcli_available():
    """Check if nmcli is available on the system."""
    try:
        subprocess.run(["nmcli", "--version"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        return True
    except FileNotFoundError:
        return False

def get_active_connection():
    """Get the active NetworkManager connection name."""
    try:
        result = subprocess.run(["nmcli", "-t", "-f", "NAME,STATE", "con", "show"], 
                              capture_output=True, text=True, check=True)
        for line in result.stdout.splitlines():
            name, state = line.split(":")
            if state == "activated":
                return name
        print("No active connection found.")
        sys.exit(1)
    except subprocess.CalledProcessError as e:
        print(f"Error getting active connection: {e}")
        sys.exit(1)

def change_dns(dns_servers):
    """Change DNS settings using NetworkManager if available, else edit /etc/resolv.conf."""
    if is_nmcli_available():
        connection_name = get_active_connection()
        dns_string = " ".join(dns_servers)
        print(f"Setting DNS to {dns_string} for connection '{connection_name}'")
        run_command(["nmcli", "con", "mod", connection_name, "ipv4.dns", dns_string])
        run_command(["nmcli", "con", "up", connection_name])
        print("DNS settings updated successfully using nmcli.")
    else:
        if os.path.exists("/etc/resolv.conf"):
            lines = []
            with open("/etc/resolv.conf", "r") as f:
                for line in f:
                    if not line.startswith("nameserver"):
                        lines.append(line)
            with open("/etc/resolv.conf", "w") as f:
                for line in lines:
                    f.write(line)
                for server in dns_servers:
                    f.write(f"nameserver {server}\n")
            print("DNS settings updated by editing /etc/resolv.conf.")
        else:
            print("Cannot find /etc/resolv.conf. DNS settings not changed.")
            sys.exit(1)

def reset_dns():
    """Reset DNS to automatic (DHCP) using NetworkManager if available, else clear /etc/resolv.conf."""
    if is_nmcli_available():
        connection_name = get_active_connection()
        print(f"Resetting DNS for connection '{connection_name}' to automatic")
        run_command(["nmcli", "con", "mod", connection_name, "ipv4.dns", ""])
        run_command(["nmcli", "con", "up", connection_name])
        print("DNS settings reset to automatic using nmcli.")
    else:
        if os.path.exists("/etc/resolv.conf"):
            lines = []
            with open("/etc/resolv.conf", "r") as f:
                for line in f:
                    if not line.startswith("nameserver"):
                        lines.append(line)
            with open("/etc/resolv.conf", "w") as f:
                for line in lines:
                    f.write(line)
            print("DNS settings reset by clearing nameservers in /etc/resolv.conf.")
        else:
            print("Cannot find /etc/resolv.conf. DNS settings not changed.")
            sys.exit(1)

def get_current_dns():
    """Get current DNS settings from /etc/resolv.conf or nmcli."""
    if is_nmcli_available():
        connection_name = get_active_connection()
        try:
            result = subprocess.run(["nmcli", "con", "show", connection_name], 
                                  capture_output=True, text=True, check=True)
            for line in result.stdout.splitlines():
                if "ipv4.dns" in line:
                    dns = line.split()[-1].split(",")
                    return dns
        except subprocess.CalledProcessError:
            return []
    else:
        if os.path.exists("/etc/resolv.conf"):
            with open("/etc/resolv.conf", "r") as f:
                nameservers = []
                for line in f:
                    if line.startswith("nameserver"):
                        nameservers.append(line.strip().split()[1])
                return nameservers
    return []

def display_menu():
    """Display the menu of options."""
    print("\nDNS Changer - Linux Console App (Inspired by Cloudflare 1.1.1.1)")
    print("Current DNS:", ", ".join(get_current_dns()) if get_current_dns() else "None")
    print("Available DNS options:")
    for i, option in enumerate(DNS_OPTIONS.keys(), 1):
        print(f"{i}. {option} ({', '.join(DNS_OPTIONS[option])})")
    print(f"{len(DNS_OPTIONS) + 1}. Custom DNS")
    print(f"{len(DNS_OPTIONS) + 2}. Reset to Automatic")
    print("0. Exit")

def main():
    while True:
        display_menu()
        choice = input("Enter your choice (0-{}): ".format(len(DNS_OPTIONS) + 2))

        if choice == "0":
            print("Exiting...")
            break
        elif choice.isdigit():
            choice = int(choice)
            if 1 <= choice <= len(DNS_OPTIONS):
                dns_servers = list(DNS_OPTIONS.values())[choice - 1]
                change_dns(dns_servers)
            elif choice == len(DNS_OPTIONS) + 1:
                custom_dns = input("Enter custom DNS servers (comma-separated, e.g., 1.1.1.1,1.0.0.1): ")
                dns_servers = [x.strip() for x in custom_dns.split(",")]
                if dns_servers:
                    change_dns(dns_servers)
                else:
                    print("Invalid input. Please provide at least one DNS server.")
            elif choice == len(DNS_OPTIONS) + 2:
                reset_dns()
            else:
                print("Invalid choice. Try again.")
        else:
            print("Please enter a valid number.")

if __name__ == "__main__":
    if os.geteuid() != 0:
        print("This script requires root privileges. Please run with sudo.")
        sys.exit(1)
    main()

This example shows a menu-driven interface, supporting predefined and custom DNS servers, with error handling and root privilege checks, mirroring the core functionality of the Cloudflare 1.1.1.1 app.

Practical Implications and User Experience

For users, this provides a lightweight, terminal-based tool that's easy to install and run, aligning with Linux's command-line culture. Developers benefit from Python's rapid prototyping and debugging, with an interesting aspect being that nmcli simplifies DNS management compared to manual file edits, though root access remains a challenge.

Legal and Security Considerations

Ensure the app adheres to platform guidelines, especially for privilege escalation, possibly using sudo prompts on Linux, and document these requirements for users.

Comparative Analysis

To clarify, here's a table comparing suitable programming languages:

This table shows Python offers the best balance of ease, system interaction, and distribution.

Conclusion

Research suggests Python is ideal for a console-based DNS-Changer app in the Linux terminal, likely using subprocess and os for system interactions. It seems likely that Python’s simplicity and wide Linux support make it perfect for quick, open-source development. The evidence leans toward handling complexities like root access, adding design challenges, but it’s feasible with Python’s capabilities, with an interesting aspect being that nmcli simplifies DNS management compared to manual edits. Use Visual Studio Code or any text editor as sufficient tools.

Key Citations

• DNS Changer for Windows, Linux, Mac operating systems
• Top 20 Best Open Source DNS Servers for (Linux / Windows)
• Best free and public DNS server of 2025 | TechRadar
• simple GUI DNS changer for linux with PyQt5
• Best Open Source DNS Software 2025
• Home
• How to Change DNS Settings in Linux
• How to Change DNS Server in Linux
• Writing DNS Applications - DNS Disco

With ncurses TUI

Key Points

• Research suggests that Python, combined with ncurses via the curses library, is an excellent choice for creating a text-based user interface (TUI) for a DNS-Changer app in the Linux terminal.
• It seems likely that curses provides robust tools for menu navigation and user input handling, enhancing usability over plain text output.
• The evidence leans toward Python’s simplicity and curses integration making it ideal for an open-source TUI solution.

Enhanced Python Example with TUI (Using curses)

Below is an updated version of the DNS-Changer app, integrating a TUI using Python’s built-in curses library. This provides a more interactive, graphical-like interface within the terminal, mimicking some GUI-like functionality without leaving the console environment.

Prerequisites

• Ensure Python 3.x is installed (python3 --version).
• The curses library is included with Python on Unix-like systems (no extra installation needed).
• Install NetworkManager if not present (sudo apt install network-manager).

Example Code

import subprocess
import os
import sys
import curses

# Predefined DNS servers
DNS_OPTIONS = {
    "Cloudflare DNS": ["1.1.1.1", "1.0.0.1"],
    "Google DNS": ["8.8.8.8", "8.8.4.4"],
    "OpenDNS": ["208.67.222.222", "208.67.220.220"]
}

def run_command(command):
    """Run a shell command with sudo and handle errors."""
    try:
        subprocess.run(["sudo"] + command, check=True)
        return True
    except subprocess.CalledProcessError as e:
        return f"Error: {e}"

def get_active_connection():
    """Get the active NetworkManager connection name."""
    try:
        result = subprocess.run(["nmcli", "-t", "-f", "NAME,STATE", "con", "show"], 
                                capture_output=True, text=True, check=True)
        for line in result.stdout.splitlines():
            name, state = line.split(":")
            if state == "activated":
                return name
        return None
    except subprocess.CalledProcessError:
        return None

def change_dns(dns_servers, stdscr):
    """Change DNS settings using NetworkManager."""
    connection_name = get_active_connection()
    if not connection_name:
        stdscr.addstr(0, 0, "No active connection found.", curses.color_pair(2))
        stdscr.refresh()
        stdscr.getch()
        return
    dns_string = " ".join(dns_servers)
    stdscr.addstr(0, 0, f"Setting DNS to {dns_string} for '{connection_name}'", curses.color_pair(1))
    stdscr.refresh()
    result = run_command(["nmcli", "con", "mod", connection_name, "ipv4.dns", dns_string])
    if result is True:
        run_command(["nmcli", "con", "up", connection_name])
        stdscr.addstr(1, 0, "DNS settings updated successfully.", curses.color_pair(1))
    else:
        stdscr.addstr(1, 0, result, curses.color_pair(2))
    stdscr.refresh()
    stdscr.getch()

def reset_dns(stdscr):
    """Reset DNS to automatic (DHCP)."""
    connection_name = get_active_connection()
    if not connection_name:
        stdscr.addstr(0, 0, "No active connection found.", curses.color_pair(2))
        stdscr.refresh()
        stdscr.getch()
        return
    stdscr.addstr(0, 0, f"Resetting DNS for '{connection_name}' to automatic", curses.color_pair(1))
    stdscr.refresh()
    result = run_command(["nmcli", "con", "mod", connection_name, "ipv4.dns", ""])
    if result is True:
        run_command(["nmcli", "con", "up", connection_name])
        stdscr.addstr(1, 0, "DNS settings reset to automatic.", curses.color_pair(1))
    else:
        stdscr.addstr(1, 0, result, curses.color_pair(2))
    stdscr.refresh()
    stdscr.getch()

def get_current_dns():
    """Get current DNS settings from nmcli."""
    connection_name = get_active_connection()
    if connection_name:
        try:
            result = subprocess.run(["nmcli", "con", "show", connection_name], 
                                    capture_output=True, text=True, check=True)
            for line in result.stdout.splitlines():
                if "ipv4.dns" in line:
                    dns = line.split()[-1].split(",")
                    return dns
        except subprocess.CalledProcessError:
            return []
    return []

def main(stdscr):
    """Main TUI function using curses."""
    # Initialize curses
    curses.curs_set(0)  # Hide cursor
    stdscr.clear()
    curses.start_color()
    curses.init_pair(1, curses.COLOR_GREEN, curses.COLOR_BLACK)  # Success messages
    curses.init_pair(2, curses.COLOR_RED, curses.COLOR_BLACK)    # Error messages

    menu_items = list(DNS_OPTIONS.keys()) + ["Custom DNS", "Reset to Automatic", "Exit"]
    current_row = 0

    while True:
        stdscr.clear()
        h, w = stdscr.getmaxyx()

        # Display title and current DNS
        title = "DNS Changer - Linux TUI"
        stdscr.addstr(0, w//2 - len(title)//2, title, curses.A_BOLD)
        current_dns = ", ".join(get_current_dns()) if get_current_dns() else "None"
        stdscr.addstr(2, 0, f"Current DNS: {current_dns}")

        # Display menu
        for idx, item in enumerate(menu_items):
            x = w//2 - len(item)//2
            y = h//2 - len(menu_items)//2 + idx
            if idx == current_row:
                stdscr.attron(curses.color_pair(1))
                stdscr.addstr(y, x, item)
                stdscr.attroff(curses.color_pair(1))
            else:
                stdscr.addstr(y, x, item)

        stdscr.refresh()

        # Get user input
        key = stdscr.getch()

        # Navigate menu
        if key == curses.KEY_UP and current_row > 0:
            current_row -= 1
        elif key == curses.KEY_DOWN and current_row < len(menu_items) - 1:
            current_row += 1
        elif key == curses.KEY_ENTER or key in [10, 13]:
            stdscr.clear()
            if menu_items[current_row] == "Exit":
                break
            elif menu_items[current_row] == "Custom DNS":
                stdscr.addstr(0, 0, "Enter custom DNS servers (comma-separated, e.g., 1.1.1.1,1.0.0.1): ")
                stdscr.refresh()
                curses.echo()
                custom_dns = stdscr.getstr(1, 0, 50).decode().strip()
                curses.noecho()
                if custom_dns:
                    dns_servers = [x.strip() for x in custom_dns.split(",")]
                    change_dns(dns_servers, stdscr)
                else:
                    stdscr.addstr(2, 0, "Invalid input. Press any key to continue.", curses.color_pair(2))
                    stdscr.refresh()
                    stdscr.getch()
            elif menu_items[current_row] == "Reset to Automatic":
                reset_dns(stdscr)
            else:
                dns_servers = DNS_OPTIONS[menu_items[current_row]]
                change_dns(dns_servers, stdscr)

if __name__ == "__main__":
    if os.geteuid() != 0:
        print("This script requires root privileges. Please run with sudo.")
        sys.exit(1)
    curses.wrapper(main)

Step-by-Step Guide to Programming with curses

1. Set Up Your Environment:
3. Write the Python Script:
   • Save the above code as dns_changer_tui.py.
4. Explanation of the Code:
   • Imports: curses is added for TUI functionality, alongside subprocess, os, and sys.
   • Color Initialization: Uses curses.start_color() and curses.init_pair() for green (success) and red (error) text.
   • Menu Navigation: Uses arrow keys (curses.KEY_UP, curses.KEY_DOWN) and Enter (curses.KEY_ENTER) for selection.
   • Dynamic Display: Centers the menu and updates based on user input, showing current DNS settings.
   • Functions: change_dns and reset_dns display status messages in the TUI, with error handling.
   • Custom Input: Allows entering custom DNS servers via a text input field using stdscr.getstr().
5. Run the App:
   • Navigate the menu with arrow keys, press Enter to select, and follow prompts for custom DNS input.
6. Test and Refine:
   • Test each option (predefined DNS, custom DNS, reset).
   • Add error handling for invalid DNS inputs or missing NetworkManager as needed.

Verify changes with:

nmcli con show "connection_name" | grep dns

Execute with sudo due to root requirements:

sudo python3 dns_changer_tui.py

Make it executable:

chmod +x dns_changer_tui.py

Create a working directory:

mkdir dns_changer_tui && cd dns_changer_tui

Verify nmcli is installed:

sudo apt install network-manager

Ensure Python 3 is installed:

sudo apt update && sudo apt install python3

How It Works

• TUI Features: The app displays a centered menu with highlighted selection, current DNS status, and interactive prompts, all within the terminal.
• User Interaction: Arrow keys move the cursor, Enter selects an option, and custom DNS input is handled with a text field.
• Feedback: Success messages appear in green, errors in red, with a pause for user acknowledgment.

Practical Implications

This TUI enhances usability over plain text input, making it more intuitive for users familiar with terminal navigation. It’s lightweight, requiring no external GUI libraries, and aligns with Linux’s console-centric culture.

Comprehensive Analysis: Adding a TUI with ncurses to a DNS-Changer App

Background

The Cloudflare 1.1.1.1 app provides a simple interface for changing DNS settings, and we aim to replicate this as an open-source console app with a TUI. ncurses (via Python’s curses) is a standard library for creating TUIs in terminals, offering menu systems, text formatting, and input handling without a full GUI.

Why curses?

• Simplicity: Built into Python, no additional dependencies needed.
• Functionality: Supports menus, colors, and keyboard navigation, ideal for a DNS-Changer.
• Compatibility: Works natively in Linux terminals, aligning with the project’s scope.

Development Steps

1. Initialize curses:
   • Use curses.wrapper() to handle setup and cleanup.
   • Disable cursor visibility and enable colors for better UX.
2. Design the Interface:
   • Center the menu dynamically based on terminal size.
   • Highlight the selected option using color pairs.
3. Handle Input:
   • Use stdscr.getch() for non-blocking keyboard input.
   • Map arrow keys and Enter to navigation and selection.
4. Integrate DNS Logic:
   • Reuse existing DNS-changing functions, adapting output for the TUI.
   • Add feedback messages directly on the screen.

Practical Implications

• Users: Gain a more polished experience, reducing errors from mistyped inputs.
• Developers: Benefit from Python’s ease and curses’s flexibility, with an interesting aspect being its lightweight nature compared to full GUI frameworks.

Conclusion

Adding a TUI with curses to the DNS-Changer app enhances its usability while keeping it console-based. Python’s integration with curses makes it an ideal choice, offering a balance of simplicity and functionality for an open-source solution.

Key Citations

• Python curses Documentation
• How to Change DNS Settings in Linux
• ncurses Programming Guide

DNS-Changer app using Flutter with Dart

Key Points

• Research suggests you can develop a DNS-Changer app using Flutter with Dart, but platform-specific code is required for each OS.
• It seems likely that Android Studio or Visual Studio Code are suitable development tools, with additional packages for permissions and processes.
• The evidence leans toward handling complexities like root access on Linux, adding design challenges, but it’s feasible with platform channels.

Project Overview

This guide walks you step-by-step through developing an open-source DNS-Changer app with Flutter and Dart, compatible with Windows, macOS, Linux, Android, and iOS. The app enables users to easily change their DNS settings, e.g., to 1.1.1.1 (Cloudflare) or 8.8.8.8 (Google), addressing platform-specific requirements like local VPNs for mobile devices and system commands for desktops.

Prerequisites

• Install the Flutter SDK from Flutter Official Documentation and Dart SDK (included with Flutter).
• Use Android Studio or Visual Studio Code with the Flutter extension for development.
• Ensure you have platform-specific SDKs: Android SDK, Xcode for iOS/macOS, Windows SDK, and Linux build tools (e.g., gcc).
• Familiarity with Dart, Flutter, and basic Android/iOS native development is helpful.

Step-by-Step Guide

Step 1: Create a New Flutter Project

• Run flutter pub get to install dependencies.

Add the process package for desktop platforms to pubspec.yaml:

dependencies:
  flutter:
    sdk: flutter
  process: ^4.2.4

Navigate to the project directory:

cd dns_changer

Open your terminal and run:

flutter create dns_changer

Step 2: Design the User Interface

• This is a basic UI. You can enhance it later, e.g., by displaying current DNS settings.

Create a simple UI in lib/main.dart, for example:

import 'package:flutter/material.dart';
import 'dart:io';
import 'package:process/process.dart';

void main() => runApp(DnsChangerApp());

class DnsChangerApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'DNS Changer',
      home: DnsChangerScreen(),
    );
  }
}

class DnsChangerScreen extends StatefulWidget {
  @override
  _DnsChangerScreenState createState() => _DnsChangerScreenState();
}

class _DnsChangerScreenState extends State<DnsChangerScreen> {
  String? selectedDns;
  final TextEditingController customDnsController = TextEditingController();

  final List<String> predefinedDns = [
    'Google DNS (8.8.8.8, 8.8.4.4)',
    'Cloudflare DNS (1.1.1.1, 1.0.0.1)',
    'OpenDNS (208.67.222.222, 208.67.220.220)',
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('DNS Changer'),
      ),
      body: Padding(
        padding: EdgeInsets.all(16.0),
        child: Column(
          children: [
            DropdownButton<String>(
              value: selectedDns,
              hint: Text('Select DNS'),
              items: predefinedDns.map((String value) {
                return DropdownMenuItem<String>(
                  value: value,
                  child: Text(value),
                );
              }).toList(),
              onChanged: (String? newValue) {
                setState(() {
                  selectedDns = newValue;
                });
              },
            ),
            TextField(
              controller: customDnsController,
              decoration: InputDecoration(
                labelText: 'Custom DNS (comma-separated)',
              ),
            ),
            SizedBox(height: 20),
            ElevatedButton(
              onPressed: () {
                String dns = selectedDns ?? customDnsController.text;
                if (dns.isNotEmpty) {
                  changeDns(dns);
                }
              },
              child: Text('Apply'),
            ),
          ],
        ),
      ),
    );
  }

  void changeDns(String dns) {
    if (Platform.isWindows) {
      List<String> dnsList = dns.split(',');
      String primary = dnsList[0];
      String secondary = dnsList.length > 1 ? dnsList[1] : '';
      String interfaceName = "Ethernet"; // Placeholder, need to get actual interface
      runCommand('netsh interface ip set dns name="$interfaceName" static $primary');
      if (secondary.isNotEmpty) {
        runCommand('netsh interface ip add dns name="$interfaceName" $secondary index=2');
      }
    } else if (Platform.isMacOS) {
      List<String> dnsList = dns.split(',');
      String command = 'networksetup -setdnsservers Wi-Fi ${dnsList.join(" ")}';
      runCommand(command);
    } else if (Platform.isLinux) {
      List<String> dnsList = dns.split(',');
      String connectionName = "Wired connection 1"; // Placeholder, need to get actual connection
      String command = 'nmcli con mod "$connectionName" ipv4.dns "${dnsList.join(" ")}"';
      runCommand(command);
      runCommand('nmcli con up "$connectionName"');
    } else if (Platform.isAndroid || Platform.isIOS) {
      // Mobile platforms, use platform channel
      static const platform = MethodChannel('com.example.dnschanger/dns');
      try {
        platform.invokeMethod('changeDns', {'dns': dns});
      } on PlatformException catch (e) {
        print("Failed to change DNS: '${e.message}'.");
      }
    }
  }

  void runCommand(String command) async {
    try {
      final process = await Process.start('sh', ['-c', command]);
      await process.exitCode;
    } catch (e) {
      print('Error running command: $e');
    }
  }
}

Step 3: Implement Platform-Specific Code

• For Desktops (Windows, macOS, Linux):
  • The above implementation uses process for system commands. Note that administrative rights may be required, handled by running as administrator on Windows or with sudo on Linux/macOS.
  • You’ll need to dynamically determine the active network interface, requiring additional code.
• For Mobile (Android and iOS):
  • For Android:
    • Create a VpnService subclass that sets up a local VPN intercepting only DNS traffic (UDP port 53).
    • Implement a DNS resolver to forward queries to the selected server, e.g., via HTTPS or plain DNS.
    • Refer to the flutter_vpn package documentation or open-source projects like Nebulo Nebulo GitHub Repository for implementation details.
  • For iOS:
    • Use NetworkExtension, e.g., NEPacketTunnelProvider or NEDNSProxyProvider, to handle DNS packets.
    • Refer to open-source projects like DNSCloak DNSCloak GitHub Repository for implementation details.
    • Note that NEDNSProxyProvider may require special entitlements from Apple.

Set up a MethodChannel to communicate with native code. Example:

static const platform = MethodChannel('com.example.dnschanger/dns');

Step 4: Handle Permissions

• On mobile devices, the app will request permissions when starting the VPN service.
• On desktops, the app may need administrative rights, managed by running with elevated privileges or user instructions.

Step 5: Test the App

• Test the app on different platforms to ensure the UI works and DNS changes are applied correctly.
• Verify on mobile devices that DNS queries are routed through the selected server.
• Verify on desktops that system DNS settings are changed.

This guide provides an overview. Implementing the native code for mobile platforms requires detailed knowledge of Android and iOS development and can be aided by studying open-source projects like Nebulo and DNSCloak.

Detailed Analysis: Developing an Open-Source DNS-Changer App with Flutter and Dart

This section provides a comprehensive analysis of developing an open-source DNS-Changer app with Flutter and Dart, compatible with Windows, macOS, Linux, Android, and iOS, focusing on the step-by-step guide for developers. The analysis draws from various sources, including official documentation, GitHub repositories, and related articles, ensuring a thorough exploration, with the current time being 01:39 PM PDT on Saturday, March 22, 2025.

Background and Context

The Domain Name System (DNS) is a critical component of internet infrastructure, translating human-readable domain names, like "example.com," into numerical IP addresses, like 192.168.0.1, that computers use to communicate. Typically, devices use DNS servers provided by Internet Service Providers (ISPs) by default, but users can configure their devices to use alternative public DNS servers like Google’s 8.8.8.8 or Cloudflare’s 1.1.1.1 for benefits like speed, privacy, or accessing blocked content. Manually changing DNS settings can be cumbersome for non-technical users, especially on mobile devices where settings are network-specific. The user specifically requests a step-by-step guide to develop an open-source DNS-Changer app with Flutter and Dart, with prior discussions emphasizing simplification and support for all mentioned operating systems.

Given the context, the analysis will explore suitable programming languages and frameworks that can cover all platforms, considering the need for system-level operations like changing DNS settings, and the tools required for development, ensuring a unified user experience.

Understanding the Requirements

A cross-platform app would need a single codebase or minimal adjustments to work on Windows, macOS, Linux, Android, and iOS, allowing users to change their system’s DNS settings to specific servers like 1.1.1.1 or 8.8.8.8, without manually editing files like /etc/resolv.conf on Linux or navigating system settings on other platforms. Changing DNS settings involves modifying network configurations, which varies by OS: for Linux, it’s often via /etc/resolv.conf or tools like NetworkManager; for Windows, through Network Settings or tools like netsh; for macOS, via System Preferences > Network > Advanced > DNS; and for mobile, via Wi-Fi settings or apps, with iOS having additional restrictions for cellular networks.

The app must:

1. Provide a UI to select or input DNS servers (e.g., 1.1.1.1, 8.8.8.8).
2. Change the system’s DNS settings accordingly, addressing platform-specific methods.

Given the complexity, the programming language and framework must support cross-platform development and allow platform-specific code when needed.

Suitable Programming Languages and Frameworks

From the analysis, Flutter with Dart stands out as the most suitable, covering all platforms with a single codebase and allowing platform-specific code via channels for DNS changes. Other options like Electron or React Native were considered but don’t cover all platforms as comprehensively.

Development Steps and Details

The step-by-step guide is based on implementing a simple UI and handling platform-specific DNS changes. Here are the detailed steps:

1. Create a New Flutter Project:
   • Create a new project with flutter create dns_changer.
   • Add the process package for desktop platforms to pubspec.yaml and run flutter pub get.
2. Design the User Interface:
   • Design a simple UI in lib/main.dart with DropdownButton for predefined DNS servers, TextField for custom DNS, and ElevatedButton to apply changes.
   • Implement basic logic to process the selected DNS, e.g., by splitting comma-separated inputs.
3. Implement Platform-Specific Code:
   • For Desktops: Use the process package to execute system commands like netsh for Windows, networksetup for macOS, and nmcli for Linux. Note that administrative rights may be required, managed by running as administrator or with sudo.
   • For Mobile: Set up a MethodChannel to communicate with native code. For Android, implement a VpnService subclass to set up a local VPN intercepting only DNS traffic, and for iOS, use NetworkExtension like NEPacketTunnelProvider or NEDNSProxyProvider to handle DNS packets. Refer to open-source projects like Nebulo Nebulo GitHub Repository for Android and DNSCloak DNSCloak GitHub Repository for iOS for implementation details.
4. Handle Permissions:
   • On mobile devices, the app will request permissions when starting the VPN service, handled by native APIs.
   • On desktops, the app may need administrative rights, managed by user instructions or automated prompts.
5. Test the App:
   • Test the app on various platforms to ensure the UI works and DNS changes are applied correctly.
   • Verify on mobile devices that DNS queries route through the selected server, and on desktops that system DNS settings are updated.

Comparative Analysis

Here’s a table comparing the implementation options:

This table highlights the differences and complexity across platforms.

Practical Implications and User Experience

For developers, using Flutter means learning Dart, which has a gentle learning curve, and leveraging its hot reload for rapid development. Users benefit from a consistent interface across platforms, with the app handling DNS change complexity, aligning with prior discussions on ease of use. An interesting aspect is that on Linux, root access for /etc/resolv.conf might surprise users, adding design complexity.

Legal and Security Considerations

Ensure the app adheres to platform guidelines, especially for mobile devices where permissions are strict. For desktops, handle privilege escalation securely, possibly using sudo prompts on Linux or UAC on Windows, and document these requirements for users.

Conclusion

Research suggests you can develop a DNS-Changer app with Flutter and Dart, but platform-specific code is required for each OS. It seems likely that Android Studio or Visual Studio Code are suitable development tools, with additional packages for permissions and processes. The evidence leans toward handling complexities like root access on Linux, adding design challenges, but it’s feasible with platform channels, with an interesting aspect being that modern browsers like Firefox on desktops support DoH, enhancing flexibility but not replacing system-wide changes.

Key Citations

• Flutter Official Documentation
• Process Package
• Nebulo GitHub Repository
• DNSCloak GitHub Repository
• Android VpnService Documentation
• iOS NetworkExtension Documentation